JP7279865B2 - Method for producing lignin-modified novolac-type phenolic resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lignin-modified novolak-type phenol resin, a method for producing the same, a molding material and resin composition containing the lignin-modified novolac-type phenol resin, and a grindstone comprising a cured product of the resin composition.

Various developments have been made so far in methods for producing lignin-modified phenolic resins. Since lignin is readily soluble in alkalis, liquid resoles obtained in the presence of base catalysis have been mainly investigated, while introduction of novolacs obtained in the presence of acid catalysis has been limited due to the low heat-meltability of lignin. . Therefore, studies have been made to utilize lignin that has been reduced in molecular weight or modified lignin by various processes and operations. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 discloses a technique for producing a lignin phenol resin having a weight average molecular weight of 5000 or less by reacting lignin having a weight average molecular weight of 5000 or less, phenols, and aldehydes in the presence of an acid catalyst. is described. In Patent Document 1, the lignin phenolic resin is used as a molding material for friction materials.

JP 2013-199561 A

However, as a result of investigation by the present inventor, it was found that the lignin phenol described in Patent Document 1 has room for improvement in terms of mechanical strength and heat resistance strength.

The inventors of the present invention have been made in view of the above problems, and found that good processability is expressed in lignin-modified novolac-type phenolic resin having a high molecular weight by highly compounding by utilizing the lignin structure. Further, the present inventors have found that a molding material having excellent mechanical properties and heat resistance can be obtained by using a lignin-modified novolac phenolic resin having a weight average molecular weight of 5500 or more, and completed the present invention.

Further, according to the present invention, there is provided a grindstone comprising a cured product of the above resin composition.

According to the invention ,
A step of mixing lignins and phenols and dispersing the lignins in the phenols to obtain a first mixture, wherein the weight average molecular weight of the lignins is 2,000 or more and 100,000 or less. and the softening point of the lignins is 110 ° C. or higher;
Simultaneously with the step of obtaining the first mixture or after the step of obtaining the first mixture, mixing the first mixture with an acid catalyst to obtain a second mixture;
A step of mixing the second mixture with an aldehyde to obtain a third mixture;
In the third mixture, the lignins, the phenols, and the aldehydes are reacted in the presence of the acid catalyst to obtain a lignin-modified novolac-type phenolic resin,
The weight average molecular weight of the lignin-modified novolac-type phenolic resin is 5500 or more,
The lignin modification rate of the lignin-modified novolak-type phenol resin is 25% or more and less than 51%.
A method for producing a lignin-modified novolak-type phenolic resin is provided.

INDUSTRIAL APPLICABILITY According to the present invention, a lignin-modified novolac-type phenol resin whose cured product has excellent mechanical properties and heat resistance, and a method for producing the same are provided.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

(lignin-modified novolac-type phenolic resin)
The lignin-modified novolac-type phenolic resin of the present embodiment has a weight average molecular weight of 5500 or more. The lignin-modified novolak-type phenolic resin of the present embodiment has a high weight average molecular weight, so that the cured product has improved mechanical strength compared to conventional lignin-modified novolak-type phenolic resins.

In one embodiment, the lignin-modified novolak-type phenol resin has a lignin-modified rate of 25% or more and 60% or less. The lignin-modified novolak-type phenolic resin of the present invention has a lignin-modified rate within the above range, so that it has excellent resin strength and is excellent in curability and moldability.

(Method for producing lignin-modified novolak-type phenolic resin)
The lignin-modified novolak-type phenolic resin having a weight average molecular weight of 5500 or more according to the present embodiment is prepared by combining lignins, phenols, and aldehydes in the presence of an acid catalyst, and the molar ratio of aldehydes to phenols (F/ It can be prepared by reacting under the condition that P) is 0.5 or more, preferably 0.5 or more and 1.2 or less. The upper limit of the molar ratio (F/P) is preferably 1.1 or less, more preferably 1.0 or less. The lower limit of the molar ratio (F/P) is preferably 0.55 or more, more preferably 0.6 or more. Lignin modification having the above-mentioned desired weight average molecular weight and lignin modification rate that achieves both workability and strength by conducting a reaction under conditions where the molar ratio (F/P) of aldehydes to phenols is within the above range. Novolak-type phenolic resins can be produced.

Materials and manufacturing conditions used for manufacturing the lignin-modified novolak-type phenolic resin of the present embodiment are described in detail below.

(Phenols)
Phenols, phenol derivatives and combinations thereof may be mentioned as the phenols used in the production of the lignin-modified novolac-type phenolic resin of the present embodiment. As the phenol derivative, phenol having an optional substituent introduced into the benzene ring can be used. Substituents include hydroxy group; lower alkyl group such as methyl group and ethyl group; halogen atom such as fluorine, chlorine, bromine and iodine; amino group; nitro group; Specific examples of phenols that can be used include phenol, catechol, resorcinol, hydroquinone, o-cresol, m-cresol, p-cresol, o-fluorophenol, m-fluorophenol, p-fluorophenol, o-chloro Phenol, m-chlorophenol, p-chlorophenol, o-bromophenol, m-bromophenol, p-bromophenol, o-iodophenol, m-iodophenol, p-iodophenol, o-aminophenol, m-amino Phenol, p-aminophenol, o-nitrophenol, m-nitrophenol, p-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, salicylic acid, p-hydroxybenzoic acid and combinations thereof etc. Phenols may be used individually by 1 type, and may be used in combination of 2 or more type.

As phenols, alkylphenols having 2 to 18 carbon atoms can also be used. Alkylphenols may have a branched chain in the alkyl chain or may have an unsaturated bond. Further, the substitution position of the alkyl chain on the benzene ring may be ortho, meta or para substitution. Examples of alkylphenols include ethylphenol, propylphenol, isopropylphenol, butylphenol, secondary butylphenol, tertiary butylphenol, amylphenol, tertiary aminophenol, hexylphenol, heptylphenol, octylphenol, tertiaryoctylphenol, nonylphenol, Tertiary nonylphenol, decylphenol, undecylphenol, dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, cardanol, curdle, urushiol, hexadecylphenol, methyl curdle, heptadecylphenol, laccol, thiol, octadecyl Phenol is mentioned. As alkylphenols, vegetable oils such as cashew nut shell liquid (cashew oil) and sumac extract can be used.

Among these, as phenols, it is preferable to use one or more selected from the group consisting of phenol, cresol, xylenol, alkylphenol and bisphenol, and from the viewpoint of production cost, phenol, cresol, butylphenol and bisphenol A are preferably used. is preferred.

(Lignins)
The lignins used in the production of the lignin-modified novolac-type phenolic resin of the present embodiment contain at least one selected from lignin and lignin derivatives.
Lignin, along with cellulose and hemicellulose, is a major structural component of plants and is one of the most abundant aromatic compounds in nature. Since lignin exists in plants as lignocellulose, part of which is bound together, lignin often refers to substances obtained from plants through decomposition, etc. Examples include kraft lignin, lignin sulfonic acid, soda pulp lignin such as lignin and soda-anthraquinone lignin; organosolv lignin; lignophenol obtained by adding phenol to high-temperature and high-pressure water-treated lignin or explosive lignin during extraction with concentrated sulfuric acid; phenolized lignin; The origin of lignin is not particularly limited, and includes wood and herbaceous plants that contain lignin and form woody parts, such as cedar, pine, cypress, and spruce. and broadleaf trees such as, rice, wheat, corn, and bamboo (herbs).

In the present embodiment, the term "lignin derivative" refers to a unit structure that constitutes lignin, or a compound that has a structure similar to the unit structure that constitutes lignin. A lignin derivative has a phenol derivative as a unit structure. Since this unit structure has carbon-carbon bonds and carbon-oxygen-carbon bonds that are chemically and biologically stable, it is less susceptible to chemical deterioration and biological decomposition.

The lignin derivatives include guaiacylpropane (ferulic acid) represented by formula (A) of formula (1) below, syringylpropane (sinapic acid) represented by formula (B) below, and formula (C) below. 4-hydroxyphenylpropane (coumaric acid) and the like. The composition of the lignin derivative varies depending on the biomass used as the raw material. Lignin derivatives containing guaiacylpropane structures are mainly extracted from conifers. Lignin derivatives containing guaiacylpropane and syringylpropane structures are mainly extracted from broad-leaved trees. Lignin derivatives containing guaiacylpropane, syringylpropane and 4-hydroxyphenylpropane structures are mainly extracted from herbs.

The lignin derivative is preferably obtained by decomposing biomass. Biomass is the result of capturing and fixing carbon dioxide in the atmosphere during the process of photosynthesis. Therefore, biomass contributes to suppressing the increase of carbon dioxide in the atmosphere. can contribute to the suppression of degeneration. Biomass includes lignocellulosic biomass. Lignocellulosic biomass includes leaves, bark, branches and wood of plants containing lignin, processed products thereof, and the like. Plants containing lignin include the above-mentioned broadleaf trees, conifers, and herbaceous plants.

Methods of decomposing biomass include chemical treatment, hydrolysis, steam explosion, supercritical water treatment, subcritical water treatment, mechanical treatment, sulfate cresol method, and pulp manufacturing method. mentioned. From the viewpoint of environmental load, a steam explosion method, a subcritical water treatment method, and a mechanical treatment method are preferable. From a cost point of view, the pulping method is preferred. Moreover, from the viewpoint of cost, it is preferable to use a by-product of biomass utilization. A lignin derivative can be prepared, for example, by decomposing biomass in the presence of various cooking liquids or solvents at 150 to 400° C. and 1 to 40 MPa for 8 hours or less. Further, lignin derivatives can be prepared by the methods disclosed in JP-A-2009-084320 and JP-A-2012-201828.

Examples of lignin derivatives include those obtained by decomposing lignocellulose in which lignin, cellulose and hemicellulose are combined. Lignin derivatives may include lignin decomposition products, cellulose decomposition products, hemicellulose decomposition products, etc., which are mainly composed of compounds having a lignin skeleton. In addition, the lignin derivative may also contain biomass-derived or process-derived inorganic substances, but when used for the application of the present embodiment, the content of inorganic substances is 10% by mass or less with respect to the entire lignin derivative used. preferable.

The lignin derivative preferably has many reaction sites on which the curing agent acts through electrophilic substitution reaction on the aromatic ring. At least one of the ortho-position and para-position of the ring is preferably unsubstituted, and lignin derived from conifers and herbs containing many guaiacyl nucleus and 4-hydroxyphenyl nucleus structures as aromatic units of lignin is preferable. As the lignin derivative, those disclosed in JP-A-2009-084320 and JP-A-2012-201828 can be used.

In addition, the lignin derivative may be a lignin derivative having a functional group (secondary derivative of lignin) in addition to the basic structure described above.

Although the functional groups possessed by the lignin secondary derivative are not particularly limited, for example, two or more of the same functional groups capable of reacting with each other or those capable of reacting with other functional groups are suitable. Specific examples thereof include epoxy groups, methylol groups, vinyl groups having carbon-carbon unsaturated bonds, ethynyl groups, maleimide groups, cyanate groups, isocyanate groups, and the like. Among these, lignin derivatives into which methylol groups are introduced (methylolated) are preferably used. Such a lignin secondary derivative undergoes self-crosslinking due to self-condensation reaction between methylol groups, and also crosslinks with alkoxymethyl groups and hydroxyl groups in the following cross-linking agent. As a result, a lignin-modified novolak-type phenolic resin having a homogeneous and rigid skeleton and excellent solvent resistance can be obtained.

Furthermore, the lignin derivative used in this embodiment may have a carboxyl group. Lignin obtained by the pulp process or high-temperature high-pressure water treatment may have carboxyl groups. A lignin-modified novolak-type phenolic resin obtained from a lignin derivative having a carboxyl group has many cross-linking points for a curing agent described below, so that the cross-linking density of the obtained cross-linked product can be improved, resulting in solvent resistance. It is possible to obtain a crosslinked product excellent in

In addition, when the lignin derivative described above has a carboxyl group, the carboxyl group can be confirmed by the presence or absence of absorption of a peak at 172 to 174 ppm when subjected to ¹³ C-NMR analysis attributed to the carboxyl group. can.

The lignins used in the production of the lignin-modified novolak-type phenolic resin of the present embodiment have a weight average molecular weight of, for example, 2,000 or more and 100,000 or less. The lower limit of the weight average molecular weight is preferably 2,500 or more, more preferably 3,000 or more, and even more preferably 4,000 or more. The upper limit of the weight average molecular weight is preferably 90,000 or less, more preferably 80,000 or less, still more preferably 75,000 or less. By using lignins having a weight-average molecular weight within the above range, the obtained lignin-modified novolac-type phenolic resin can have excellent curability and the cured product can have high mechanical strength. The weight-average molecular weight is a polystyrene-equivalent number-average molecular weight measured by gel permeation chromatography, and can be determined by the method in Examples.

The lignins used in the production of the lignin-modified novolak-type phenolic resin of the present embodiment have a number average molecular weight of, for example, 200 or more and 5,000 or less. The lower limit of the number average molecular weight is preferably 300 or higher, more preferably 350 or higher, and even more preferably 400 or higher. The upper limit of the number average molecular weight is preferably 4,000 or less, more preferably 3,000 or less, and even more preferably 2,000 or less. Lignins having a number-average molecular weight within the above range are preferable because they are excellent in reactivity and therefore excellent in workability in the production process of the lignin-modified novolac-type phenolic resin. Moreover, by using lignins having a number average molecular weight within the above range, the obtained lignin-modified novolak phenolic resin can have excellent curability, and the cured product thereof can have high mechanical strength. The number average molecular weight is a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography, and can be determined by the method in Examples.

Here, an example of the method for measuring the molecular weight by the above-mentioned gel permeation chromatography will be explained.
In the method of measuring molecular weight by gel permeation chromatography, first, a lignin derivative is dissolved in a solvent to prepare a measurement sample. The solvent used at this time is not particularly limited as long as it can dissolve the lignin derivative, but from the viewpoint of the measurement accuracy of gel permeation chromatography, for example, tetrahydrofuran and N-methyl-2-pyrrolidone are preferable. . Since the lignins of the present embodiment can contain insoluble matter due to biomass, process-derived inorganic substances, and plant-derived high molecular weight organic matter, the molecular weight of the lignins is obtained by selecting an appropriate solvent and filtering the insoluble matter. be done. In order to increase the lignin modification rate of the obtained lignin-modified novolak-type phenol resin, the insoluble content of the lignins used is preferably 30% by mass or less in an appropriate solvent. The molecular weight of the lignin-modified novolac-type phenolic resin can be similarly obtained by filtering the insoluble matter. The content of insoluble matter in the lignin-modified novolak-type phenol resin is preferably 15% by mass or less, more preferably 10% by mass or less. When the amount of the content is in the above range, the lignin-modified novolac phenolic resin has good curability, and can be cured uniformly.

Next, the GPC system “HLC-8320GPC (manufactured by Tosoh)” is connected in series with “TSKgelGMHXL (manufactured by Tosoh)”, which is an organic general-purpose column packed with a styrenic polymer packing material, and “G2000HXL (manufactured by Tosoh)”. do. Into this GPC system, 200 μL of the measurement sample described above is injected, the tetrahydrofuran of the eluent is developed at 40 ° C. at 1.0 mL / min, and the differential refractive index (RI) and ultraviolet absorbance (UV) are used. measure time. The number average molecular weight and weight average molecular weight of the target lignins can be calculated from the calibration curve showing the relationship between the retention time and molecular weight of standard polystyrene prepared separately. Refractive index is preferred as the detection mode.

The molecular weight of the standard polystyrene used to create the calibration curve is not particularly limited, but for example, weight average molecular weights of 1,090,000, 427,000, 190,000, 96,400, Standard polystyrenes of 37,900, 18,100, 10,200, 5,970, 2,630, 1,050 and 500 (manufactured by Tosoh) can be used.

The softening point of the lignins used in the production of the lignin-modified novolak-type phenolic resin of the present embodiment is preferably 90°C or higher, more preferably 110°C or higher, and even more preferably 130°C or higher. On the other hand, lignins with high softening points that cannot be measured can be used. When such lignins are used to produce a lignin-modified novolak-type phenolic resin with a high degree of modification, the resulting modified novolac-type phenolic resin has a high molecular weight, low fluidity, and poor workability. However, the lignin-modified novolak-type phenolic resin of the present embodiment has unexpectedly good processability despite the high lignin-modified rate obtained from such lignins and the high molecular weight lignin-modified phenolic resin. .

The volatile content of the lignins used in the present embodiment is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. When the volatile content of the lignins is within the above range, the reactivity of the lignins can be improved, and the reaction rate of the resulting lignin-modified novolac-type phenolic resin can be increased. The main volatile matter is often water. For example, it is calculated by spreading 4 g in an aluminum cup and drying it at 80° C. for 20 hours.

The softening point of lignins can be measured according to JISK2207 using a ring and ball type softening point tester (for example, ASP-MG2 type manufactured by Meltec Co., Ltd.). When the lignin contains a large amount of water, it is measured after being completely dried at 70°C or less. In this embodiment, for example, if a good sample cannot be prepared due to the heat melting property of lignins with a hot plate of 150 to 200° C., it is determined that the softening point is too high to be measured.

When using lignins obtained by decomposing biomass, a large amount of low-molecular-weight components may be mixed in, which may cause volatile matter and odor during heating and a decrease in softening point. These components can be used as they are, or can be removed by heating or drying the lignins to adjust the softening point and odor.

(aldehydes)
Aldehydes used in the production of the lignin-modified novolac-type phenolic resin of the present embodiment include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, and n-butyraldehyde. , caproaldehyde, allylaldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde, paraxylene dimethyl ether and the like. Preferred are formaldehyde, paraformaldehyde, trioxane, polyoxymethylene, acetaldehyde, paraxylene dimethyl ether and combinations thereof. Aldehydes may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, it is preferable to use formaldehyde or acetaldehyde from the viewpoint of productivity and low cost.

(acid catalyst)
As the acid catalyst used in the production of the lignin-modified novolak-type phenolic resin of the present embodiment, any acid catalyst can be used as long as it can be used as a reaction catalyst, and organic acids, inorganic acids, and combinations thereof can be used. Organic acids include acetic acid, formic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, benzoic acid, salicylic acid, sulfonic acid, phenolsulfonic acid, p-toluenesulfonic acid and the like. Inorganic acids include hydrochloric acid, sulfuric acid, sulfate esters, phosphoric acid, phosphate esters, and the like.

In the production of the lignin-modified novolac-type phenolic resin of the present embodiment, the molar ratio (F/P) of aldehydes to phenols is, for example, 0.5 or more, preferably 0.55 or more, more preferably is greater than or equal to 0.6. The upper limit of the molar ratio (F/P) of aldehydes to phenols is, for example, 1.2 or less, preferably 1.1 or less, and more preferably 1.0 or less. By carrying out the reaction under conditions where the molar ratio (F/P) of aldehydes to phenols is within the above range, a lignin-modified novolac type having a weight average molecular weight of 5500 or more and improved workability and strength. A phenolic resin can be obtained.

In the production of the lignin-modified novolak-type phenolic resin of the present embodiment, the step of reacting lignins, phenols, and aldehydes in the presence of an acid catalyst includes heating lignins and phenols at 70°C to 120°C. The following step of mixing under heating to disperse lignins to obtain a mixture (step 1), a step of mixing an acid catalyst simultaneously with step 1 or after step 1 (step 2), and after step 2, A step of mixing aldehydes (step 3) may be included. Further, the step of reacting lignins, phenols and aldehydes in the presence of an acid catalyst is carried out at a temperature of, for example, 60°C to 120°C, preferably 80°C to 100°C. , with a reaction time of 10 minutes to 100 minutes. This allows the reaction to proceed efficiently and sufficiently. In addition, by heating, the starting materials are uniformly mixed, and the resulting lignin-modified novolak-type phenolic resin can be cured uniformly due to intermolecular entanglement and intermolecular action, and thus has excellent dimensional accuracy. Molding can be achieved. The reaction time is not particularly limited, and may be appropriately determined according to the type of starting materials, the molar ratio of the mixture, the amount and type of catalyst used, and the reaction conditions. Furthermore, the reaction mixture after the reaction may be post-treated. For post-treatment, for example, distillation under heating (eg, 150° C. or higher), distillation under normal pressure, distillation under reduced pressure, or a combination thereof can be used.

Although it is preferable to carry out the above steps 1, 2 and 3 without a solvent, an organic solvent or water may be used as the solvent. Hydrous lignin may be used instead of adding water. Examples of organic solvents include alcohols, ketones, esters, ethers, and hydrocarbons. Alcohols include methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin and the like. Ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone and the like. Esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methoxybutyl acetate, amyl acetate, methyl lactate, ethyl lactate, butyl lactate and the like. Ethers include propyl ether, dioxane, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, methyl carbitol, ethyl carbitol. , butyl carbitol, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate. Hydrocarbons include toluene, xylene, pentane, hexane, cyclohexane, heptane, octane, decane, solvent naphtha, industrial gasoline, petroleum ether, petroleum benzine, ligroin and the like. These may be used alone or in combination of two or more.

Here, in the conventional method of increasing the molecular weight of the lignin-modified novolac-type phenolic resin by adjusting the reaction ratio of phenols, lignins, and aldehydes, the viscosity of the reactants increases, making it difficult to dehydrate. was sometimes longer. In addition, there were cases where a large amount of unreacted phenols remained.
In contrast, the method of the present embodiment can shorten the process time and increase the yield of the resin compared to the conventional case of increasing the molecular weight at the reaction ratio of phenols, lignins and aldehydes. be able to. In addition, by adjusting the molar ratio (F / P) of aldehydes to phenols in the above range, and adjusting the molecular weight, molecular weight distribution, and addition amount of the lignins used, the characteristics and The physical properties of the resin material can be adjusted within a desired range.

The lignin-modified novolac-type phenolic resin of the present embodiment obtained by the above method has a weight average molecular weight of 5500 or more. The weight average molecular weight of the lignin-lignin-modified novolak-type phenolic resin of the present embodiment is, for example, 5,500 or more and 50,000 or less, preferably 6000 or more and 45,000 or less, more preferably 7,000 or more and 40, 000 or less. The lignin-modified novolac-type phenolic resin having a weight average molecular weight within the above range has excellent curing properties, and the cured product thereof has high mechanical strength. The lignin-modified novolac-type phenol resin of the present embodiment has a lignin modification rate of 25% or more and 60% or less, preferably 30% or more and 55% or less, more preferably 35% or more and 55% or less. . The lignin-modified novolac-type phenol resin of the present invention has a lignin-modified rate within the above range, so that it has excellent resin strength and heat resistance, and is excellent in curability and moldability.

The lignin-modified novolak-type phenolic resin of the present embodiment can be provided in the form of fine powder, granules, pellets, and varnish, for example. The form of the lignin-modified novolak-type phenolic resin can be appropriately selected depending on the application.

(molding material)
The lignin-modified novolak-type phenolic resin of the present embodiment obtained as described above is suitably used as a molding material for transfer molding and injection molding, for example. More specifically, the lignin-modified novolac-type phenolic resin of the present embodiment described above is molded by blending a curing agent (crosslinking agent) and, if necessary, other components, and kneading at a predetermined temperature. Provided as material. A molding material containing the lignin-modified novolak-type phenolic resin of the present embodiment can be injection-molded, and its molded article is excellent in mechanical properties such as strength and elastic modulus.

As the curing agent used for the molding material of this embodiment, for example, an amine-based curing agent can be used. Specifically, hexamethylenetetramine, hexamethoxymethylolmelamine, and the like can be used as the amine-based curing agent. As the amine-based curing agent, for example, hexamethylenetetramine is preferably used.

The content of the curing agent is, for example, 7 to 30 parts by weight, preferably 10 to 25 parts by weight, with respect to 100 parts by weight of the lignin-modified novolac-type phenolic resin. A molding material having good curability can be obtained by setting the amount within the above numerical range.

The molding material of this embodiment may further contain a filler. That is, the molding material can contain a lignin-modified novolak-type phenolic resin, a curing agent and a filler.

As the filler, for example, a fiber base material, an organic filler, an inorganic filler, or the like can be used. A fibrous base material is a filler having a fibrous form. The organic fillers and inorganic fillers may be either particulate fillers or platelet fillers, respectively. A plate-like filler is a filler having a plate-like shape. A particulate filler is a filler having a shape other than fibrous or plate-like, including irregular shapes. These may be used alone or in combination of two or more.

Granular fillers include, for example, granular inorganic fillers such as glass beads, glass powder, calcium carbonate, talc, silica, aluminum hydroxide, clay and mica.

Examples of fibrous fillers include glass fiber, carbon fiber, asbestos fiber, metal fiber, wollastonite, attapulgite, sepiolite, rock wool, aluminum borate whisker, potassium titanate fiber, calcium carbonate whisker, titanium oxide whisker, fibrous inorganic fillers such as ceramic fibers; fibrous organic fillers such as aramid fibers, polyimide fibers, poly(paraphenylenebenzobisoxazole fibers); May be used in combination.

Plate-like fillers and granular fillers include, for example, talc, kaolin clay, calcium carbonate, zinc oxide, calcium silicate hydrate, mica, glass flakes, glass powder, magnesium carbonate, silica, titanium oxide, and alumina. , aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, aluminum borate, calcium borate, sodium borate, aluminum nitride, boron nitride, silicon nitride, fibrous Pulverized fillers and the like can be mentioned.

The content of the filler in the molding material is, for example, 25 parts by mass to 500 parts by mass, preferably 50 parts by mass to 400 parts by mass, more preferably 100 parts by mass of the lignin-modified novolac-type phenolic resin. is 100 parts by mass to 300 parts by mass. A molding material containing the lignin-modified novolak-type phenolic resin can have excellent mechanical strength by setting it to the above lower limit or more. By making it equal to or less than the above upper limit, production stability of the crosslinked body (molded body) can be enhanced.

The resin material for manufacturing the molded article of the present embodiment can contain other components other than the components described above within a range that does not impair the object of the present invention. Examples of other components include additives such as elastomers, curing accelerators, resin components, release agents, pigments, flame retardants, adhesion improvers, and coupling agents.

Examples of the elastomer include, but are not particularly limited to, acrylonitrile-butadiene rubber, isoprene, styrene-butadiene rubber, ethylene-propylene rubber, and the like. Among these, acrylonitrile-butadiene rubber is preferred. Toughness can be imparted particularly by using an elastomer.

The curing accelerator is not particularly limited, and ordinary curing accelerators can be used. For example, oxides or hydroxides of alkaline earth metals such as magnesium oxide, calcium hydroxide, barium hydroxide, salicylic acid and aromatic carboxylic acids such as benzoic acid. The curing accelerator is used in an amount of, for example, 0.5 to 20 parts by mass with respect to 100 parts by mass of the lignin-modified novolac-type phenolic resin.

Examples of the resin component include urea resins, resins having a triazine ring such as melamine resins, bismaleimide resins, polyurethane resins, silicone resins, resins having a benzoxazine ring, cyanate ester resins, polyvinyl butyral resins, and polyvinyl acetate. resin. Moreover, these multiple types can also be used in combination if necessary.

Examples of the release agent include stearic acid, calcium stearate, zinc stearate, and polyethylene.

Examples of the pigment include carbon black.

The resin material of the present embodiment is obtained by melting and kneading a lignin-modified novolak-type phenol resin, a curing agent, and a filler, if used, with a kneader, a roll, etc. in advance, and then uniformly mixing with the above other components, or , All raw material components to be blended are melt-kneaded by a kneading device such as a roll, a co-kneader, a twin-screw extruder, or a combination of rolls and other mixing devices, and then granulated or pulverized. In this embodiment, the molding material is provided in the form of powder, granules, tablets, sheets, or the like.

By heat-treating and molding the obtained molding material, it is possible to obtain a molded article (crosslinked body) composed of a cured product of this molding material. The method of molding the molding material is not particularly limited, but transfer molding, compression molding, injection molding and the like can be used, for example.

Molded articles of the present embodiment include, for example, automobiles, aircraft, railroad vehicles, ships, general-purpose machines, household appliances, cooking utensils and molded articles used for peripheral parts thereof, or their housings, structural and mechanical parts. , molded products used for electric and electronic parts.

(resin composition)
The lignin-modified novolac-type phenol resin of the present embodiment is suitably used as a resin composition for resinoid grindstones. More specifically, the lignin-modified novolac-type phenolic resin of the present embodiment described above is provided as a powdery resin composition for a resinoid grindstone by blending hexamethylenetetramine. The resin composition of the present embodiment contains the lignin-modified novolac-type phenol resin of the present embodiment and hexamethylenetetramine, so that it has excellent curability, and the cured product of the resin composition is used as a grindstone. It has an appropriate degree of mechanical strength and elastic modulus. The resin composition of the present embodiment is provided, for example, in the form of granules. When the resin composition is provided in the form of powder particles, it is preferable to pulverize the resin composition so that the average particle diameter is 10 μm or more and 60 μm or less from the viewpoint of handling. From the viewpoint of grindstone strength, 15 μm or more and 45 μm is more preferable.

In the resin composition of the present embodiment, the amount of hexamethylenetetramine is preferably 2% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 17% by mass, relative to the lignin-modified novolac-type phenol resin. % or less, more preferably 8 mass % or more and 15 mass % or less. If the amount of hexamethylenetetramine is less than the above lower limit, curing of the lignin-modified novolac-type phenolic resin may be insufficient. Cracks and blisters may occur in the resulting cured product.

(Whetstone)
The resin composition of the present embodiment described above is used to produce a resinoid grindstone. The resinoid grindstone of the present embodiment is obtained by adding abrasive grains to the resin composition described above, but other fillers, additives, and the like can be optionally used. Abrasive grains that can be used include, for example, alumina oxide, silicon carbide, diamond, etc., and these play a role in developing the grinding performance of the whetstone. Examples of fillers that can be used include inorganic fillers such as cryolite, iron sulfide, iron oxide, barium sulfate, and quicklime, and organic fillers such as thermosetting resin powder, rice husks, and wood flour. It plays a role in improving the grinding performance of the grindstone. Examples of additives that can be used include silane coupling agents, furfuryl alcohol, furfural, creosote oil, other organic solvents, or liquid resol-type phenolic resins, which improve adhesion with abrasive grains. Therefore, it can be used after wetting the surface of the abrasive grains.

As a method for producing a resinoid grindstone from the resin composition of the present embodiment, for example, first, liquid resol-type phenolic resin is mixed with abrasive grains and well kneaded to obtain abrasive grains with wet surfaces, and then the abrasive grains of the present embodiment are obtained. a powdery resin composition containing lignin-modified novolak-type phenolic resin and hexamethylenetetramine, and if necessary, the above fillers and additives are added to prepare resin-coated grains; The resulting resin-coated grains are molded into a desired shape with a mold heated to room temperature or 40 to 80° C., and the molded product is heated and sintered for 10 to 50 hours. . The conditions for heating and firing are not particularly limited, but, for example, the temperature may be raised from room temperature to 200° C. over 10 to 24 hours, held at the peak temperature for 3 to 10 hours, and then gradually cooled.

The grindstone of this embodiment obtained by the above method has excellent bending strength and water resistance, and therefore has excellent grinding performance.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.
Examples of embodiments will be added below.
1. A lignin-modified novolac-type phenol resin having a weight average molecular weight of 5,500 or more.
2. 1. The lignin modification rate of the lignin-modified novolak-type phenol resin is 25% or more and 60% or less. lignin-modified novolac-type phenolic resin according to .
3. 1. or 2. A lignin-modified novolak-type phenolic resin according to
The lignin-modified novolak-type phenolic resin is obtained by combining lignins, phenols, and aldehydes in the presence of an acid catalyst, and the molar ratio (F/P) of the aldehydes to the phenols is 0.5 or more. A lignin-modified novolak-type phenolic resin obtained by reacting under certain conditions.
4. 3. The weight average molecular weight of the lignins is 2,000 or more and 100,000 or less. lignin-modified novolac-type phenolic resin according to .
5. 1. to 4. A molding material comprising the lignin-modified novolak-type phenolic resin according to any one of 1 and a curing agent.
6. 1. to 4. A resin composition comprising the lignin-modified novolac-type phenol resin according to any one of 1 and hexamethylenetetramine.
7. 6. It is powdery with an average particle size of 10 μm or more and 60 μm or less; The resin composition according to .
8. 7. A grindstone made of a cured product of the resin composition according to 1.
9. Lignin modification by reacting lignins, phenols, and aldehydes in the presence of an acid catalyst under conditions where the molar ratio (F/P) of the aldehydes to the phenols is 0.5 or more. including a step of obtaining a novolak-type phenolic resin;
The weight average molecular weight of the lignin-modified novolak-type phenol resin is 5500 or more,
A method for producing a lignin-modified novolak-type phenolic resin.
10. 9. The lignin modification rate of the lignin-modified novolak-type phenol resin is 25% or more and 60% or less. A method for producing a lignin-modified novolac-type phenolic resin according to .
11. 8. The lignin has a weight average molecular weight of 2,000 or more and 100,000 or less. or 10. A method for producing a lignin-modified novolac-type phenolic resin according to .
12. 8. The lignins contain volatile matter in an amount of 60% by mass or less; 11. A method for producing a lignin-modified novolak-type phenolic resin according to any one of the above.
13. The step of reacting lignins, phenols, and aldehydes in the presence of an acid catalyst under conditions where the molar ratio (F/P) of the aldehydes to the phenols is 0.5 or more,
A step of mixing the lignins and the phenols to obtain a mixture;
simultaneously with the step of obtaining the mixture or after the step of obtaining the mixture, mixing the acid catalyst;
a step of mixing the aldehydes after the step of mixing the acid catalyst;
Atmospheric pressure and / or vacuum distillation at 150 ° C. or higher,
9. 12. A method for producing a lignin-modified novolak-type phenolic resin according to any one of the above.

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

[Examples A1 to A5, Comparative Examples A1 to A3]
<Preparation of lignin-modified novolac-type phenolic resin>

(Preparation Example A1)
(Preparation of Lignin Derivative) First, a lignin derivative used for synthesizing a lignin-modified novolak-type phenolic resin was prepared by the following procedure.
To 1500 parts by weight of cedar wood flour with a moisture content of 50%, 5000 parts by weight of pure water as a cooking liquid, 180 parts by weight of sodium hydroxide, 120 parts by weight of sodium carbonate and 7.5 parts by weight of 9,10-anthraquinone as a cooking aid. , charged into a stainless steel autoclave facility with a capacity of 10 L, and subjected to a digestion reaction at 170°C for 3 hours while stirring. After the reaction, the cooking liquor was cooled to room temperature, the pulp component was removed with a screen, and the black liquor containing lignin was separated. Dilute sulfuric acid was added to the separated black liquor to adjust the pH to 8, and the resulting precipitate was centrifuged. After washing twice with 500 parts by mass of water, the precipitate was suspended in 5 times the amount of water and readjusted to pH 2 with dilute sulfuric acid. The precipitated lignin is centrifuged again, washed with water, filtered under suction, spread on a vat, air-dried, and dried in a vacuum oven at 70°C or less. 150 parts by weight (in terms of solid content) were obtained from parts by mass. The solid content of lignin was calculated from the residual rate after putting a 4 g sample in an aluminum cup and drying it by heating at 135° C. for 1 hour.
(Preparation of lignin-modified phenolic resin) Subsequently, a lignin-modified novolak-type phenolic resin was synthesized by the following procedure.
Add 100 parts by weight of phenol to a four-necked flask equipped with a stirrer, a cooling tube and a thermometer, gradually add 40 parts by weight of the lignin derivative solid content, mix and disperse at 60 ° C. or higher, and add 1 part of oxalic acid. .4 parts by weight was added, and 58.6 parts by weight of a 37% formaldehyde aqueous solution was slowly added over 60 minutes and reacted at 100°C. C. or higher, and when the desired phenol concentration was achieved, the mixture was taken out to obtain 128.1 parts by weight of lignin-modified novolac-type phenolic resin A1.

(Preparation Example A2)
(Preparation of lignin derivative) Preparation Example A1 except that, when adjusting the pH to 2 and centrifuging, adding water again and centrifuging increased the number of water washings and drying at 80°C or less in a vacuum oven. A lignin derivative was prepared by the same method.
(Preparation of lignin-modified phenolic resin) Same as Preparation Example A1 except that 40 parts by weight of lignin derivative solid content and 1.4 parts by weight of oxalic acid were added to 100 parts by weight of phenol and mixed at 70°C or higher for 30 minutes. As a result, 127.9 parts by weight of lignin-modified phenolic resin A2 was obtained.

(Preparation Example A3)
(Preparation of lignin derivative) As a cooking liquor, 5000 parts by weight of pure water, 150 parts by weight of sodium hydroxide, 80 parts by weight of sodium sulfide, 70 parts by weight of sodium carbonate, and 7.5 parts by weight of 9,10-anthraquinone as a cooking aid. The same as Preparation Example A1 except that it was used, and when adjusting to pH 2 and centrifuging, adding water again and centrifuging to increase the number of water washings and drying at 80 ° C. or less in a reduced pressure oven. A lignin derivative was prepared by the method.
(Preparation of lignin-modified phenolic resin) To 100 parts by weight of phenol, 37.4 parts by weight of lignin derivative solid content and 1.5 parts by weight of oxalic acid were added and mixed at 70°C or higher for 30 minutes to prepare 51 parts by weight of 37% formaldehyde aqueous solution. 124.2 parts by weight of lignin-modified phenolic resin A3 was obtained in the same manner as in Preparation Example A1 except that 2 parts by weight was used.

(Preparation Example A4)
(Preparation of lignin derivative) Beech wood flour having a moisture content of 50% is digested at 195°C for 1 hour using 3000 parts by weight of ethanol and 2250 parts by weight of water as a cooking liquor, and ethanol is fractionally distilled from the cooking liquor. A lignin derivative was obtained in the same manner as in Preparation Example A1 except that the obtained aqueous solution was centrifuged and freeze-dried to obtain a lignin derivative having a solid content of 90% or more.
(Preparation of lignin-modified phenolic resin) Preparation example except that 100 parts by weight of phenol, 60 parts by weight of lignin derivative solid content, and 1.6 parts by weight of oxalic acid were added, and 51.6 parts by weight of 37% formaldehyde aqueous solution was used. 138.1 parts by weight of lignin-modified phenolic resin A4 was obtained in the same manner as A1.

(Preparation Example A5)
(Preparation of lignin derivative) A lignin derivative was obtained in the same manner as in Preparation Example A1.
(Preparation of lignin-modified phenolic resin) 100 parts by weight of phenol, 41.7 parts by weight of lignin derivative solid content and 1.4 parts by weight of oxalic acid were added, and 57.8 parts by weight of a 37% formaldehyde aqueous solution was added to obtain the desired phenol. 140.6 parts by weight of lignin-modified phenolic resin A5 was obtained in the same manner as in Preparation Example A1, except that 2.1 parts by weight of cashew shell oil was added, mixed and taken out after reaching the concentration.

(Preparation Example A6)
(Preparation of lignin derivative) 200 parts by weight of cedar wood powder having a moisture content of 50% and 567 parts by weight of pure water as a cooking liquid were placed in a stainless steel autoclave with a capacity of 10 L, and treated at 300°C for 1 hour while stirring. rice field. The digested liquor after the reaction was cooled to room temperature and filtered to obtain a solid content containing lignin. The resulting solid content was immersed in 250 parts of acetone for 12 hours. This was filtered, and 15.2 parts by weight of the lignin derivative was obtained by distilling off acetone from the filtrate at 70° C. or less and drying.
(Preparation of lignin-modified phenolic resin) Preparation Example A1 except that 100 parts by weight of phenol, 43.5 parts by weight of lignin derivative solid content, 1.4 parts by weight of oxalic acid, and 73.3 parts by weight of 37% aqueous formaldehyde solution were used. 143.7 parts by weight of lignin-modified phenolic resin A6 was obtained in the same manner as above.

(Preparation Example A7)
(Preparation of Lignin Derivative) A lignin derivative was obtained in the same manner as in Preparation Example A3, except that beech wood flour having a water content of 50% was used. Further, the lignin derivative was dispersed in acetone, filtered, and the acetone was removed from the filtrate at 70° C. or lower, followed by drying to obtain a low molecular weight lignin derivative.
(Preparation of lignin-modified phenol resin) Preparation Example A1 was used except that 100 parts by weight of phenol, 33.3 parts by weight of lignin derivative solid content, 1.3 parts by weight of oxalic acid, and 58.6 parts by weight of 37% aqueous formaldehyde solution were used. Similarly, 121.6 parts by weight of lignin-modified phenolic resin A7 was obtained.

The weight-average molecular weight, number-average molecular weight, and softening temperature of the obtained lignin derivative were measured by the GPC method or the ring and ball softening point tester, respectively. The results are shown in Table 1 as "Characteristics of Lignin".
Also, the weight average molecular weight, number average molecular weight and lignin modification rate of the obtained lignin-modified novolac phenolic resin were measured. These measurement results are shown in Table 1 as "Characteristics of lignin-modified phenolic resin". In addition, since the lignin-modified novolac phenol resin component of the present embodiment may contain a component with a particularly high molecular weight, the value excluding the high molecular weight component exceeding the standard polystyrene number average molecular weight of 42,7000 is also referred to in the table ( ). written inside.

<Production of molding material>
In each example and each comparative example, 15 parts by mass of hexamethylenetetramine (curing agent) was added to 100 parts by mass of the lignin-modified phenol resin shown in Table 1 at room temperature, and pulverized and mixed to prepare a phenol-modified lignin resin composition. .
To the resulting phenol-modified lignin resin composition, glass fiber (filler, glass milled fiber, manufactured by Nitto Boseki Co., Ltd., standard fiber diameter 10 ± 1.5 µm, average fiber length 90 µm) 160 parts by weight, additives ( Stearic acid (manufactured by NOF Corporation) and 8 parts by weight of carbon black (manufactured by Mitsubishi Chemical Corporation, #5)) were blended, kneaded with a heating roll at about 90 ° C. for about 5 minutes, cooled and pulverized, and phenol-modified lignin. A resin composition (molding material) was obtained.
(Phenolic resin)
Phenolic resin A1: lignin-modified novolak-type phenolic resin A1 of Preparation Example A1
Phenolic resin A2: lignin-modified novolac-type phenolic resin A2 of Preparation Example A2
Phenolic resin A3: lignin-modified novolak-type phenolic resin A3 of Preparation Example A3
Phenolic resin A4: lignin-modified novolac-type phenolic resin A4 of Preparation Example A4
Phenolic resin A5: lignin-modified novolac-type phenolic resin A5 of Preparation Example A5
Phenolic resin A6: lignin-modified novolac-type phenolic resin A6 of Preparation Example A6
Phenolic resin A7: lignin-modified novolac-type phenolic resin A7 of Preparation Example A7
- Phenolic resin A8: unmodified novolak-type phenolic resin A8 (Mw = 9640, Mn = 940)

(Performance evaluation of molding material)
The obtained molding material was subjected to transfer molding under the conditions of 175° C., 20 MPa, and 3 minutes, and further heat-treated at 180° C. for 8 hours to obtain a molded product (hardened product). The obtained molded article was evaluated for the following items. Table 1 shows the results.

(Bending strength (25°C), bending elastic modulus (25°C))
The flexural modulus and flexural strength were measured at 25° C. in accordance with JIS K 6911 “General Test Methods for Thermosetting Plastics”. Specifically, a three-point bending test was performed by applying a load at a rate of 2 mm/min using a precision universal testing machine (Autograph AG-Xplus manufactured by Shimadzu Corporation).
(Bending strength (150°C), bending elastic modulus (150°C))
At 150° C., the flexural modulus and flexural strength were measured in the same manner as above.
(Charpy impact strength)
The Charpy impact strength was measured according to JIS K 6911 "General test method for thermosetting plastics".
(insulation resistance)
Insulation resistance was measured according to JIS K 6911 "General test method for thermosetting plastics".

[Examples B1 to B3, Comparative Examples B1 to B2]
<Preparation of lignin-modified novolac-type phenolic resin>
A lignin-modified novolac-type phenolic resin was prepared by the method shown in each preparation example.

(Preparation Example B1)
(Preparation of lignin derivative) As a cooking liquor, 5000 parts by weight of pure water, 150 parts by weight of sodium hydroxide, 80 parts by weight of sodium sulfide, 70 parts by weight of sodium carbonate, and 7.5 parts by weight of 9,10-anthraquinone as a cooking aid. A lignin derivative was obtained in the same manner as in Preparation Example A1, except that it was used.
(Preparation of lignin-modified phenolic resin) Preparation Example A1 was prepared except that 100 parts by weight of phenol, 37.4 parts by weight of lignin derivative solid content, 1.5 parts by weight of oxalic acid, and 51.2 parts by weight of 37% aqueous formaldehyde solution were used. 125.0 parts by weight of lignin-modified phenolic resin B1 was obtained in the same manner as above.

(Preparation Example B2)
(Preparation of lignin derivative) Beech wood flour having a moisture content of 50% is digested at 195°C for 1 hour using 3000 parts by weight of ethanol and 2250 parts by weight of water as a cooking liquor, and ethanol is fractionally distilled from the cooking liquor. A lignin derivative was obtained in the same manner as in Preparation Example A1 except that the obtained aqueous solution was centrifuged and freeze-dried to obtain a lignin derivative having a solid content of 90% or more.
(Preparation of lignin-modified phenolic resin) Preparation Example A1 except that 100 parts by weight of phenol, 38.5 parts by weight of lignin derivative solid content, 1.4 parts by weight of oxalic acid, and 55.2 parts by weight of 37% formaldehyde aqueous solution were used. 123.3 parts by weight of lignin-modified phenolic resin B2 was obtained in the same manner as above.

(Preparation Example B3)
(Preparation of lignin derivative) Beech wood flour having a moisture content of 50% is digested at 195°C for 1 hour using 3000 parts by weight of ethanol and 2250 parts by weight of water as a cooking liquor, and ethanol is fractionally distilled from the cooking liquor. A lignin derivative was obtained in the same manner as in Preparation Example A1 except that the obtained aqueous solution was centrifuged and freeze-dried to obtain a lignin derivative having a solid content of 90% or more.
(Preparation of lignin-modified phenolic resin) Preparation Example A1 except that 100 parts by weight of phenol, 79.2 parts by weight of lignin derivative solid content, 1.8 parts by weight of oxalic acid, and 51.7 parts by weight of 37% formaldehyde aqueous solution were used. 156.7 parts by weight of lignin-modified phenolic resin B3 was obtained in the same manner as above.

The weight-average molecular weight, number-average molecular weight, and softening temperature of the obtained lignin derivative were measured by the GPC method or the ring and ball softening point tester, respectively. The results are shown in Table 1 as "Characteristics of Lignin".
Also, the weight average molecular weight, number average molecular weight and lignin modification rate of the obtained lignin-modified novolac phenolic resin were measured. These measurement results are shown in Table 1 as "Characteristics of lignin-modified phenolic resin".
In addition, since the lignin-modified novolak phenol resin component of the present embodiment may contain a component with a particularly high molecular weight, the value excluding the high molecular weight component exceeding the standard polystyrene number average molecular weight of 427,000 is also referred to in the table ( ). written inside.

<Preparation of resin composition>
In each example and each comparative example, 100 parts by mass of the lignin-modified phenolic resin shown in Table 2 and 10 parts by mass of hexamethylenetetramine as a curing agent were mixed and pulverized with a pulverizer to a particle size of 10 to 60 μm. A powdery resin composition was obtained.
(Phenolic resin)
Phenolic resin B1: lignin-modified novolac-type phenolic resin B1 of Preparation Example B1
Phenolic resin B2: lignin-modified novolak-type phenolic resin B2 of Preparation Example B2
- Phenolic resin B3: lignin-modified novolak-type phenolic resin B3 of Preparation Example 3
- Phenolic resin B4: lignin-modified novolak-type phenolic resin A6 of Preparation Example A6
- Phenolic resin B5: unmodified novolac-type phenolic resin B5 (Mw = 12640, Mn = 1204)

(Performance evaluation of powdery resin composition)
The flow of the obtained powdery resin composition was measured by the following method.
(flow)
Using a powdery resin composition obtained by mixing and pulverizing 100 parts by weight of phenolic resin or lignin-modified phenolic resin and 10 parts by weight of hexamethylenetetramine, flow A method of JIS K 6910 "Phenolic resin test method" The flow (flow) was measured according to.
The longer the flow of the powdered resin composition, the higher the strength of the cured product.

<Preparation of grindstone test piece>
In each example and each comparative example, 1200 parts of alumina abrasive grains, Sacrandom A#60 (manufactured by Nihon Carlit Co., Ltd.) and 24 parts of wetter liquid phenolic resin PR-55331 (manufactured by Sumitomo Bakelite Co., Ltd.) were used. After kneading for 4 minutes using a Shinagawa kneader, 144 parts of each phenolic resin or unmodified phenolic resin prepared in the above preparation example was added and further kneaded for 2 minutes to produce coated grains. The state of the coated grains was checked immediately after kneading and after storage for 12 hours at 25° C. and 60% relative humidity. After that, the coated grain was put into a mold and press-molded so that the molded product had a size of 100 mm×25 mm×15 mm and a bulk specific gravity of 2.0, and the molded product was placed on a stainless iron plate. Place this in a hot air circulation dryer with a programmable function, and dry from room temperature to 80°C for 5 hours, from 80°C to 100°C for 5 hours, from 100°C to 120°C for 10 hours, from 120°C to 130°C for 4 hours. 130° C. to 170° C. for 7 hours, held at 180° C. for 10 hours, and then cooled to room temperature over 5 hours for curing to produce a grindstone test piece.

(Performance evaluation of grindstone test piece)
The obtained grindstone test pieces were evaluated for the following items. Table 2 shows the evaluation results.

(Room temperature bending strength, room temperature bending elastic modulus)
The flexural modulus and flexural strength were measured at 25° C. in accordance with JIS K 6911 “General Test Methods for Thermosetting Plastics”. Specifically, a three-point bending test was performed by applying a load at a rate of 2 mm/min using a precision universal testing machine (Autograph AG-Xplus manufactured by Shimadzu Corporation).
(Water resistance strength)
The water resistance strength was measured by immersing the test piece in water at 80° C. for 2 hours, taking it out, and measuring it under the same conditions as the room temperature bending strength.
(Heat resistant strength)
The heat resistance strength was measured under the same conditions as those for room temperature bending strength by setting a test piece and allowing it to stand at 200° C. in a constant temperature bath for 15 minutes. Table 2 shows the results.

This application claims priority based on Japanese Patent Application No. 2021-064596 filed on April 6, 2021, and the entire disclosure thereof is incorporated herein.

Claims (4)

A step of mixing lignins and phenols and dispersing the lignins in the phenols to obtain a first mixture, wherein the weight average molecular weight of the lignins is 2,000 or more and 100,000 or less. and the softening point of the lignins is 110 ° C. or higher;
Simultaneously with the step of obtaining the first mixture or after the step of obtaining the first mixture, mixing the first mixture with an acid catalyst to obtain a second mixture;
A step of mixing the second mixture with an aldehyde to obtain a third mixture;
In the third mixture, the lignins, the phenols, and the aldehydes are reacted in the presence of the acid catalyst to obtain a lignin-modified novolac-type phenolic resin,
The weight average molecular weight of the lignin-modified novolac-type phenolic resin is 5500 or more,
The lignin modification rate of the lignin-modified novolak-type phenol resin is 25% or more and less than 51%.
A method for producing a lignin-modified novolak-type phenolic resin. The step of obtaining the third mixture includes mixing aldehydes into the second mixture so that the molar ratio (F/P) of the aldehydes to the phenols is 0.5 or more,
The step of reacting the lignins, the phenols, and the aldehydes in the presence of the acid catalyst in the third mixture comprises: the lignins, the phenols, and the aldehydes and the lignin-modified novolac type according to claim 1 , which is a step of reacting in the presence of the acid catalyst under conditions where the molar ratio (F / P) of the aldehydes to the phenols is 0.5 or more. A method for producing a phenolic resin. The method for producing a lignin-modified novolac-type phenolic resin according to claim 1 or 2 , wherein the lignins contain volatile matter in an amount of 60% by mass or less. After the step of obtaining a lignin-modified novolac-type phenolic resin by reacting the lignins contained in the third mixture, the phenols, and the aldehydes in the presence of the acid catalyst,
Further comprising a step of atmospheric pressure and / or vacuum distillation at 150 ° C. or higher,
A method for producing a lignin-modified novolac-type phenolic resin according to any one of claims 1 to 3 .